A combustion variation detecting apparatus for an internal combustion engine for detecting variations in combustion using variations in torque and rotation of the internal combustion engine has been proposed, as disclosed in, for example, JP-A-64-38624. More specifically, the apparatus calculates indicated torque based on an output signal from a cylinder pressure sensor disposed in part of cylinders. A difference between a torque mean value calculated from a history of past indicated torque and the indicated torque calculated is then calculated to find a torque variation. The torque variation is then used to detect a combustion variation.